Measurement and correlation of excess enthalpies for water+ethanol+1-buthyl 3-methylimidaozolium tetrafluoroborate system

It is difficult to find physical properties data for systems containing ionic liquids, excess molar enthalpies, binary interaction parameter, etc. In this study, the excess molar enthalpies were measured for water+ethanol+ionic liquid system using a isothermal microcalorimeter at 298.15 K. The ionic liquid used was 1-butyl 3-methyl imidazolium tetrafluoroborate, [BMIM] [BF₄]. The isothermal microcalorimeter (IMC) is a flow-type calorimeter that measures the heat of mixing directly, using specific mixing cell. By employing NRTL, electrolyte-NRTL and UNIQUAC models, binary interaction parameters were determined and investigated for the correlation with vapor liquid equilibrium (VLE). The e-NRTL model with the partial dissociation was employed to correlate the ionic liquid system. The binary data of VLE system were used from literatures. Specifically, UNIQUAC volume and surface area parameters were determined using Bondi radius.     

A new process for fuel ethanol dehydration based on modeling the phase equilibria of the anhydrous MgCl2 + ethanol + water system

The use of ethanol as a fuel for motor engines has attracted significant attention because of its possible environmental and economic advantages over fossil fuel. However, the energy demand for the ethanol dehydration process significantly impacts its production cost. A new and energy efficient process is developed on the basis of salt extractive distillation, which uses recycled MgCl₂ granules as a separating agent. Vapor‐liquor‐equilibria (VLE) data for the ternary MgCl₂ + ethanol + water system, and the three constituent binary systems were measured at 30, 60, 90, and 101.3 kPa. A large enhancement of relative volatility of the ethanol + water system in the presence of MgCl₂ is observed throughout the entire ethanol concentration range, which completely broke the azeotrope. The salt effect of MgCl₂ is thought to be the result of energetic interactions and the hydration equilibrium reaction of the Mg²⁺ ion with water molecules. The calculation results by the mixed‐solvent electrolyte model embedded in the OLI platform equipped with new model interaction parameters and equilibrium constant (obtained via the regression of experimental VLE data), provided for a satisfactory means of simulating the MgCl₂ salt extractive distillation process. Finally, the process was proven feasible at the laboratory‐scale resulting in large granules of recovered MgCl₂ and a product of 99.5 wt % ethanol. © 2014 American Institute of Chemical Engineers AIChE J, 61: 664–676, 2015     

Thermodynamics and separation process for quaternary acrylic systems

Vapor‐liquid equilibrium (VLE) and liquid‐liquid equilibrium (LLE) data of binary and ternary acrylic systems were systematically measured. Subsequently, VLLE phase diagrams of binary systems, tridimensional VLE phase diagrams of methyl acrylate (MA)‐methanol (Me)‐H₂O ternary system, and quaternary LLE phase diagrams of MA‐Me‐H₂O‐methyl acetate (MeOAc) system were constructed. These diagrams clearly demonstrated the effects of temperature on phase equilibrium. The experimental data was fitted by the NRTL and UNIQUAC models, and the best‐fitted parameters were used to predict interaction properties of ternary and quaternary mixture. Therefore, the phase equilibrium data were provided as reference for the design of acrylic systems rectification or extraction process. Residue curve was mapped out for MA‐Me‐H₂O system through Aspen plus software. Finally, using thermodynamics and residue curve as theoretical basis, two novel separation processes were proposed and applied to the quaternary acrylic systems. © 2015 American Institute of Chemical Engineers AIChE J, 62: 228–240, 2016     

(CO2 + 2‐propanol) mixture as a foaming agent for polystyrene: A simple thermodynamic model for the high pressure VLE‐phase diagrams taking into account the foam vitrification

The equation of state model developed by Lacombe and Sanchez (J Phys Chem 1976, 80, 2352) is used in the form proposed later by Sanchez and Stone (Polymer Blends, Vol. 1: Formulation, 2000; Chapter 2) to correlate experimental vapor‐liquid equilibrium (VLE) data for the three binaries and the ternary systems. Experimental data from the binary systems carbon dioxide‐isopropyl alcohol (CO₂‐IPrOH), isopropyl alcohol‐polystyrene (IPrOH‐PS), and carbon dioxide‐polystyrene (CO₂‐PS) are used to calculate VLE properties for the ternary system CO₂‐IPrOH‐PS. Two‐dimensional VLE‐phase diagrams were calculated and used to describe from a thermodynamic point of view the pressure, volume, and temperature values that characterize a thermoplastic foam evolution process, from the extruder to the foaming die. For different initial mixture CO₂ + IPrOH concentrations, pressure reduction produces liquid foaming until the vitrification curve arrests the final foam volume expansion. The dependence of the vitreous transition with the system CO₂ + IPrOH concentration while foaming is represented by the Chow (Macromolecules 1980, 13, 362) equation. The calculation procedure is proposed as a design tool to reduce the amount of experimental data usually needed as a requirement previous to the design stage. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2663–2671, 2007     

Modeling of Nitrogen and Carbon Dioxide Solubility in Alternative Fuels at High Pressures Using the Soave‐Redlich‐Kwong Equation of State

In this paper, the Soave‐Redlich‐Kwong equation of state with quadratic mixing rule has been tested for correlation of vapor‐liquid equilibria (VLE) at high pressures in the binary nitrogen + dimethyl ether, dimethyl ether + methanol, nitrogen + methanol, carbon dioxide + dimethyl ether and carbon dioxide + methanol systems. The interaction parameters k_ij were evaluated for each binary pair and used for prediction of VLE in the ternary nitrogen + dimethyl ether + methanol and carbon dioxide + dimethyl ether + methanol systems at high pressures. The results of correlation and prediction are discussed.     

Salt effect of CACL2, NH4i and NAI on vapor-liquid equilibrium of ethanol + water system at 298.15 K

Salt effect on vapor-liquid equilibrium for the ethanol + waiter system was measured at 298.15 K using an experimental apparatus based on the static method. The salting-out effect of CaCl₂, NH₄I and NaI on the ethanol + water system follows the order of CaCl₂ > NaI > NH₄I. The observed experimental data were correlated by the use of a semi-empirical model proposed by Hála (1983) with an accuracy of ± 2.13%. The application of Hála's model was confirmed in the ethanol + water system to be added the salts other than CaCl₂ at 298.15 K.     

Prediction of phase equilibrium of CO2/cyclic compound binary mixtures using a rigorous modeling approach

Vapor liquid equilibrium (VLE) data has significant role in designing processes which include vapor and liquid in equilibrium. Since it is impractical to measure equilibrium data at any desired temperature and pressure, particularly near critical region, thermodynamic models based on equation of state (EOS) are usually used for VLE estimating. In recent years due to the development of numerical tools like artificial intelligence methods, VLE prediction has been find new alternatives.In the present study a novel method called Least-Squares Support Vector Machine (LSSVM) used for predicting bubble/dew point pressures of binary mixtures containing carbon dioxide (CO₂) + cyclic compounds as function of reduced temperature of the system, critical pressure, acentric factor of the cyclic compound, and CO₂ composition. A 333 binary equilibrium data points of CO₂ and six cyclic compounds within temperature and pressure ranges of 308.15–473.15 K and 0.5–27.71 MPa were used to develop the model. Results show that the proposed model is able to predict VLE data for binary systems containing supercritical or near-critical CO₂/cyclic compounds with an acceptable average absolute relative deviation percent (AARD%) of 3.9381% and the coefficient of determination (R²) value of 0.9980. For detection of the probable doubtful experimental data, and applicability of the model, the Leverage statistical approach performed on the data sets. This algorithm showed that the proposed LSSVM model is statistically valid for VLE prediction and the whole phase equilibrium data points are in applicability domain of the model.     

Enhanced solubility of hydrogen and carbon monoxide in propane‐ and propylene‐expanded liquids

Conventional propylene hydroformylation occurs in a gas‐expanded liquid phase. Reliable knowledge of the phase equilibria of such systems, including the solubilities of CO and H₂ in propylene‐expanded solvents, is essential for rational process design and development. Herein, we report the vapor–liquid equilibrium (VLE) data of the following ternary systems involving CO, H₂, propane, propylene, toluene and NX‐795 at temperatures from 70 to 90°C and pressures up to 1.5 MPa: propane/H₂/toluene, propane/CO/toluene, propylene/H₂/toluene, propylene/CO/toluene, propane/H₂/NX‐795, propane/CO/NX‐795, propylene/H₂/NX‐795 and propylene/CO/NX‐795. The solubilities of H₂ and CO in either propane‐expanded or propylene‐expanded phases are observed to be greater than those in the neat organic solvents, by as high as 78% at 70°C and 1.5 MPa. By modeling the vapor and the liquid phases as pseudo‐binary systems, the Peng‐Robinson equation of state (PR‐EoS) with van der Waals’ mixing rules and binary interaction parameters is shown to satisfactorily predict the experimental VLE data. © 2017 American Institute of Chemical Engineers AIChE J, 64: 970–980, 2018     

利用二元体系的C-H红外光谱推算汽液平衡数据

Prediction of vapor-liquid equilibrium (VLE) is extremely necessary to separate liquid mixture in chemical production, especially when the required experimental data are difficult to measure, or the measurement is not economical. The infinite dilution activities can be used to predict VLE. However, it needs both thc ends of the activities that are difficult to obtain for many systems. In the present study, a new model is proposed for correlating the frequency shift of C-H stretching band of IR spectra over the whole concentration. Investigated mixtures include water/2-propanol, water/N, N-dimethylformamide (DMF), water/methanol, water/ethanol, water/1, 4-dioxane,and water/dimethylsulfoxidc (DMSO) systems. Simultaneous correlations of C-H frequency shift and VLE data arc made. Furthermore, the VLE data were predicted with satisfactory results by the parameters obtained from IR spectra coupled with one of the infinite dilution activity coefficients.     

利用二元体系的C H红外光谱推算汽液平衡数据

Prediction of vapor-liquid equilibrium （VLE） is extremely necessary to separate liquid mixture in chemical production, especially when the required experimental data are difficult to measure, or the measurement is not economical. The infinite dilution activities can be used to predict VLE. However, it needs both the ends of the activities that are difficult to obtain for many systems. In the present study, a new model is proposed for correlating the frequency shift of C-H stretching band of IR spectra over the whole concentration. Investigated mixtures in- clude water/2-propanol, water/N, N-dimethylformamide （DMF）, water/methanol, water/ethanol, water/1, 4-dioxane, and water/dimethylsulfoxide （DMSO） systems. Simultaneous correlations of C--H frequency shift and VLE data are made. Furthermore, the VLE data were predicted with satisfactory results by the parameters obtained from IR spectra coupled with one ot the intinite chlution activity coefficients.     

Modelling Vapour − Liquid Equilibrium of CO2 in Aqueous N‐Methyldiethanolamine through the Simulated Annealing Algorithm

The modified Clegg‐Pitzer equation is used to correlate and predict the vapor‐liquid equilibrium of the CO₂‐MDEA‐H₂O system. Simulated annealing (SA), a computational stochastic technique for finding near global minimum solutions to optimization problems, has been used for parameter estimation in the model to predict VLE of CO₂ in aqueous MDEA solution. The solubility of CO₂ in aqueous solutions of 23.8 wt % and 30.0 wt % of N‐methyldiethanolamine (MDEA) has been measured over the temperature range of 303‐323 K and CO₂ partial pressure range of 1 to 100 kPa. The model predicted equilibria have been found to be in good agreement with the experimental results of VLE measurement of this work as well as those in the open literature. In this work, the SA technique has been used as an alternative to the traditional Levenberg‐Marquardt (LM) technique, to predict the VLE data accurately.     

甲醇-乙酸-丙酸多元体系汽液平衡

用新型泵式沸点仪测定了在100kPa下甲醇-乙酸、甲醇-丙酸、乙酸-丙酸3个二元体系以及甲醇-乙酸-丙酸三元系在不同液相组成时的沸点,并用间接法T-p-x(温度、压力和液相摩尔分数)推算了3个二元体系的汽相平衡组成。3个二元体系活度系数分别用Wilson模型、NRTL模型、Margules模型和van Laar模型进行关联,用最小二乘法求出了它们的液相活度系数模型参数,同时,用这些模型参数来计算它们的汽相摩尔分数。所得的液相活度系数来计算3个二元体系的过量吉布斯自由能函数,且所研究的所有体系中各组分之间不存在共沸点。用3个二元体系Wilson模型参数对所测的三元体系数据进行关联,建立该系统汽液平衡的热力学模型并计算平衡时的汽相摩尔分数和泡点温度。由面积积分法检验这些模型参数计算的3个二元体系相平衡数据,得到很好的热力学一致性。     

High‐pressure phase equilibria for a styrene/CO2/polystyrene ternary system

To reveal the possibility of supercritical (SC)‐CO₂‐assisted devolatilization of polystyrene, the equilibrium composition data for the CO₂ phase in a styrene/CO₂/polystyrene ternary system is determined by a semistatic experimental technique. The parameters in the lattice–fluid equation of state of Sanchez and Lacombe are determined for the investigated system. The distribution coefficients of styrene between the polymer and the supercritical fluid phases are investigated experimentally at 318 and 328 K over the pressure range of 12–20 MPa. The binary interaction parameter between styrene and CO₂ is obtained by regression of the vapor–liquid equilibrium data. The interaction parameter between CO₂ and polystyrene is calculated by using the sorption data from the literature, and the interaction parameter between styrene and polystyrene is optimized by using the measured data of this study. The investigation of the distribution coefficients indicates that styrene can be removed from polystyrene by SC‐CO₂ at near room temperature and moderately high pressures. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1938–1944, 2002     

Measurement and correlation of the isothermal vapor-liquid equilibrium data for carbon dioxide and dimethyl ether system

Vapor-liquid equilibrium (VLE) data for the binary system of carbon dioxide (CO₂)+dimethyl ether (DME) were measured at six equally spaced (10 K) temperatures between 283.15 and 333.15 K. The data in the two-phase region were measured by using a circulation-type equilibrium apparatus in which both vapor and liquid phases are continuously recirculated. The equilibrium compositions of vapor and liquid phases and pressure were reported at each temperature. The experimental VLE data were correlated with PR-EoS using the Wong-Sandler (W-S) mixing rule and the universal mixing rule (UMR). The overall average values of AAD-P (%) and AAD-y through the temperature range from 283.15 to 333.15 K were 1.0% and 0.012 for the W-S mixing rule and 0.88% and 0.014 for the UMR, respectively. All values are small and acceptable. Calculated results with these equations have given satisfactory results compared with the experimental data.     

Vapor–liquid equilibria for ethyl acetate + methanol and ethyl acetate + ethanol mixtures: Experimental verification and prediction

This work aims of the determination of a series of vapor–liquid equilibrium (VLE) experimental data at low pressure (70 kPa) for binary mixtures of ethyl acetate with methanol and ethanol. The Fischer's ebulliometer was used for the measurements of VLE data. A complete series of equilibrium data was obtained such as pressure, temperature and compositions of the liquid and vapor phases (PTxy). The two VLE data sets were submitted to a thermodynamic consistence test, where the deviations were evaluated in all variables, using the UNIQUAC activity coefficient equation. The magnitude of the average deviations was within the experimental uncertainty satisfying the Gibbs–Duhen equation. The data sets were also used to test the prediction of the UNIFAC model in its original and modified editions and the results were also within experimental uncertainties. Then a series of binary systems containing alcohols (methanol and ethanol) and esters (methyl and ethyl acetate) were collected from the literature for testing systematically the capability of the UNIFAC contribution method for this type of mixtures.     

The thermodynamics and separation process design for the ternary system 1,3-propanediol + 1,3-butanediol + 2,3-butanediol

ABSTRACT

The isobaric vapor–liquid equilibrium (VLE) data at 101.3kPa for (1,3-propanediol(PG) + 1,3-butanediol(BD)), (1,3-PG+2,3-BD) and (1,3-BD+2,3-BD) and for the ternary system of (1,3-PG+1,3-BD+2,3-BD) have been measured. The thermodynamic properties of the non-ideal vapor phase have been considered with the EOS equation. The liquid activity coefficients have been calculated with Wilson, NRTL and UNIQUAC equations, and the binary interaction parameters were regressed by these models. The vapor composition of VLE data were calculated by the optimum parameter group and generated a good consistency to experimental values. Based on all the preceding results, a two-column distillation process was designed.     

Modeling high pressure vapor–liquid equilibrium of ternary systems containing supercritical CO2 and mixed organic solvents using Peng–Robinson equation of state

High pressure vapor–liquid equilibrium (VLE) of CO₂-expanded organic solvents was investigated using Peng–Robinson-LCVM-UNIFAC equation of state. Bubble pressure of several ternary mixtures was predicted using this model and correlations were developed based only on binary experimental data. A sensitivity study of the LCVM parameter numerical value was done by considering the coherence between the mathematical features of the mixing rule and the quality of the simulation. The results provided by PR-LCVM-UNIFAC were compared with those ones given by Peng–Robinson equation of state using the classical quadratic mixing rules (PR-CMR). Despite the use of two adjustable parameters for each binary system, PR-CMR is not able to provide good results when applied to ternary systems. The capability of PR-LCVM-UNIFAC model to predict liquid mixture density for ternary systems using parameters regressed only from bubble pressure experimental data was also investigated. Due to the lack of liquid density experimental data, it was possible to perform only a qualitative assessment of the density curves calculated by this equation of state.     

丙烷-乙醇-水体系相平衡研究

提出了改进的DDLC-MH(81)状态方程,用于丙烷-乙醇-水体系二元汽液平衡数据的关联计算,其模型参数与温度有良好的线性关系.并用汽相循环法测定了该体系在不同温度下的二元及三元VLE数据,结果与模型的推算值取得良好的一致.并用模型预测了超临界丙烷条件下的三元相平衡数据.结果表明,在液相乙醇浓度高于0.2的情况下,超临界丙烷比超临界二氧化碳有更高的乙醇溶解度和选择性.     

Experimental Study of the Salt Effect in Vapor/Liquid Equilibria Using Headspace Gas Chromatography

The salt effect on vapor/liquid equilibrium for an ethanol/water system was studied at 70 °C using the Headspace Gas Chromatography technique. The azeotropic point of the system was eliminated in the presence of the salts studied. All the salts investigated in this work exhibited a salting out effect which followed the order of NH₄Cl > NaCl > CaCl₂ and which increased with increasing salt concentration. Good agreement with Furter's equation was observed for the experimental data with unsaturated NaCl salt. The salt effect parameter, determined from Furter's equation, was found to be a function of the liquid concentration.